Data dictionary link provided in ticket as this is one way to review all data element definitions in one place.

Some definitions are lacking, others have text that belongs in the comment section of the definition. 

For example: Brachytherapy Treatment Phase: Modality

• The modality for the brachytherapy procedure
• This text does not define modality. 
• If you follow it back to the extension - the description of the extension is "Extension capturing a modality of external beam or brachytherapy radiation procedures"  - still no definition of modality. 
  • On a side note - if the extension is specific to external beam or brachytherapy radiation, the name should be ExternalBeamOrBrachytherapyModality

Example: Radiotherapy Volume Morphology

• The text: "
  Although the name of the element is 'morphology', this element is defined in the base resource as 'The kind of structure being represented by the body structure'. The name is somewhat of a misnomer, and might be better interpreted simply as 'type' or 'kind'."  belongs in the comment, not as part of the definition. 

Example: Tumor Specimen, Tumor Identifier

• The text "To associate this with a specific BodyStructure conforming to the Tumor profile, add an identifier with a value that matches a persistent identifier from `BodyStructure.identifier.value` that is unique in the context of the Patient." is not a definition, but instructions on how to value the element.  

Rather than go through each and every item, suggest that the element definitions be reviewed, especially those for new profiles with the terminology SMEs.